The overall goal of this multi-disciplinary 2-year project is to engage an active collaborative partnership between researchers in atmospheric chemistry and infectious diseases for development of rapid diagnostic tools based on the detection and identification of informative trace gases in the exhaled breath and/or blood from individuals with infection. We first carry-out investigations of experimental animal models of infection, first at the BSL2 level of containment and then, as procedures become refined, at the BSL3 level. The specific aims are the following: (1) Further development of gas signature detection and analysis using animal models of Borrelia and Salmonella. Samples of exhaled breath and blood from the infected animals and control animals will be analyzed using advanced gas chromatographic techniques with one-of-a-kind capability for broad and reproducible detection of volatile organic compounds in the parts per trillion range. We also are assessing the contributions of selected other variables besides infection on trace gases in the exhaled breath and blood. These include age, sex, MHC background, and normal flora. Once there has been characterization with one or more models of bacterial infection of mice, we will extend the analysis to selected viral infections of experimental models at the BSL2 level. (2) Application of gas signature analysis to experimental animal models of pulmonary and systemic infection with Burkholderia pseudomailei in first mice and then hamsters as a second species. Gas signatures will be correlated with pathogen burdens and distributions in the animals, disease severity and outcome, and various biomarkers of host responses. We anticipate that some informative gas signatures will be attributable to host response to infection or to a unique interaction between pathogen and mammalian host.